Pipe line cleaning method



J. E. Lol-:FFLER ET AL, 2,767,138

PIPELINE CLEANING METHOD 6 5 9 nl...v 6, 1 a 0 Filed Jan. 13. 1954 MQIDOW M Ol N PIPE LINE CLEANING METHOD John E. Loetller(l and Obert L. Nardin, Houston, Tex., assignors to Thornhill-Craver Company, Inc., Houston, Tex., acorporation of Texas Application January 1s, 1954, sei-rar No. 403,112 2 claims. (cl. 21o-16) This invention relates to new and useful improvements in pipe line cleaning method, and particularly to methods and apparatus for yremoving foreign particles from petroleum liquids flowing in a pipe line.

One of the most serious problems in the transporta-tion of uids, such as petroleum liquids through pipe lines, has been the internal corrosion of such pipe lines. In recent years, the problem of corrosion in pipe lines has been accentuated by the increased distances which petroleum uids are transported. Under the present practice, the petroleum fluids are transported from the petroleum fields to the refineries and then from the refineries to the ultimate consumers who in many instances are thousands of miles from the petroleum fields. Due to the miles of pipe line thus required, it has becomel increasingly dificult to prevent corrosion in pipe lines.

The corrosion of the pipe lines presents a two-fold problem, namely, in the corrosion `of the pipe itself, and also in the corrosion products, which are largely iron compounds or particles, which occur in the pipe lines and thus contaminate the petroleum uids delivered to the ultimate consumers. These corrosion products may enter the petroleum liquid at the storage tanks or other equipment at the refinery or may come from a section of corroded pipe in the pipe line, but in any event, regardless of their source, it is known that they are largely responsible for the initiation of corrosion in the pipe line during the transportation of the uids therethrough. These iron particles attach themselves tothe pipe line and form a nucleus for a corrosion spot. Once such a corrosion spotis formed, the corrosion then proceeds at a fairly rapid rate.

In order to remove corrosion products, dirt and similar foreign particles from a pipe line, it has been the practice in the past to run mechanical scraper units through the-pipe line for various intervals of the pipe length. Such mechanical scrapers are intended to remove the 4corrosion products in a pipe line, but 'they are expensive and also are difficult to handle in use. Furthermore, the removal of the corrosion products in the pipe line by such scraper units generally results ina release of the corrosion products without entirely removing same so that they are subsequently picked up and mixed with the petroleum liquids passing through the pipe. Y

Another factor which enters into the problem of the removal ofy corrosion products and other foreign particles from liquids in a pipe line or other liquid conductor is that said products or particles `are generally of a size less than 40 microns, and in many instances are only 1 micron or less in size. Particles of such small size are not removable from liquids by the known filter screens or strainers, and so far as is known, no process has beenheretofore provided for the removal of particles of a size less than 40 microns while utilizing the usual filter screens or strainers.

It is, therefore, one object of this invention to provide an improved method and apparatus for removing foreignV particles, and particularly corrosion products, from fluids 2,767,138 Patented ct. 16, 1.956

such as petroleum uids owing through a pipe line or other tiuid conductor.

It is an important object of this invention to provide a method and apparatus for removing from a liquid foreign particles, such vas corrosion products and dirt of such a size that they cannot ordinarily be removed from the liquid by the known lter screens or strainers, by inserting into the liquid a material capable of attaching to said particles to form an increased particle size capable of being subsequently removed from the liquid by said -known screens or strainers.

Another object of this invention is to provide a meth-v od and apparatus for removing foreign particles such as corrosion products from fluids flowing in a pipe line, by the continuous injection of a filter material into the pipe line in quanti-ties varied in accordance with the amount of the foreign particles in the uid to be removed, whereby the uid can be rendered free or substantially free from such foreign particles.

Still another object of this invention is to provide a method and apparatus for removing foreign particles in a pipe line having a tuid flowing therethrough, by the injection into the'pipe line at a point of tlow of the fluid of a material capable of attaching toV said foreign particles, such as diatomaceous earth, carbon black, and activated alumina, and after the fluid and said material have traveled a predetermined distance, then to filter said material and foreign particles adhering thereto from the liuid with a filter screen or strainer, whereby a clean uid is delivered downstream in the pipe line.

A further object of this invention is to provide a method and apparatus for removing foreign particles from a iiuid, such as petroleum liquids, by rst precoating a strainer with a predetermined quantity of material capable of adhering to said foreign particles and thereafter injecting another quantity of said material upstream from the strainer so -that the foreign particles become associated with said material as it ows downstream, the other quantity of said material and the foreign particles attached thereto being removed by passing the uid through the precoated strainer, whereby a porous layer of said material-and said foreign particles is formed on the precoated-screen to thereby assure filtering action over an extended period of time without materiallyreducing the quantity of ow or requiring a material increase in pressure to obtain al constant ow through the strainer and the layers formed thereon.

The construction designed to carry out the invention will be hereinafter described together with other features thereof.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown, and wherein:

Figure 1 is a diagrammatic view of the usual pipe linel 1). YThis pipe line 10 for the transportation of the fluidsA may extend for thousands of miles and it will have associated therewith at various intervals of about 35 to 50 miles stations or substations 12 and terminals 14 which are adapted to perform necessary operations in the transportation of the liuids through the pipe line 10 and in the delivery of the uids to the consumer. Thus, such great lengths of pipe line are used today in the transportation 3 of petroleum uids that the problems of preventing or retarding corrosion in such lines, and the delivery of fluids free from corrosion products, as well as other foreign particles including color-forming particles, have become of paramount importance.

Briey, the method of this invention involves the injection into a fluid of a material or agent which is capable of attaching to foreign particles such as corrosion products in the uid as the luid is flowing in a pipe line to thereby enable the removal of such particles or products from the iiuids. Thus, the foreign particles are adhered to the particle-attaching material while the huid is ilowing and prior to the removal of the particles and material by a strainer so that units of combined foreign particle and particle-attaching material contact the strainer. Such combined units form layers on a strainer stream which are extremely porous whereby filtration through the strainer can be continued at a substantially constant rate without materially increasing the pressure differential across the layers, even though the layers build up to a considerable thickness. Also, such combined particle and material units are considerably larger in size than the separate particles or material so that effective filtering can be obtained with a strainer screen instead of conventional filter cloth type filters.

lnsofar as the lapparatus of this invention is concerned, it briefly includes a mixing chamber Z3 wherein the particle-attaching material is mixed with a portion of the uid fed thereto from the pipe line l@ through by-pass inlet pipe 20. The particle-attaching material is thus placed in a fluid condition Without diverting the rnain uid owing in the pipe line 10. The material is fed into the mixing chamber 23 from hopper 3@ in amounts which are varied in accordance with the amount of foreign particles detected by the detector means all. The by-passed uid with the dissolved material therein is returned from the mixing chamber 23 to the pipe line 10 through rthe return pipe 35, with pump 3d preferably being utilized for the return feeding. flows through a section of the pipe line 10 directly to a strainer and during that tlow in the pipe line and prior to reaching the strainer, the particle-attaching material adheres or attaches to the foreign particle in the iluid to form the combined units of particle and material.

The invention is particularly concerned with the removal of foreign particles from flowing liquids, wherein the particles are of such a small size that they cannot be removed by known strainers or screens, and generally it may be stated, that particles of a size less than 40 microns would be the main concern of this invention. The particular foreign particles removed from liquids by the method of this invention may vary, but in the treating of petroleum lluids by the method of this invention, the most common foreign particles are corrosion products, dirt and color-forming matter. Various types of materials or agents are suitable in this invention, the main require- 5 ment being that they are capable of attaching or adhering to the foreign particles in the liquid. Throughout this specification and the claims, the term particle-attaching material" is used to define the suitable materials, examples of which include diatomaceous earth, carbon black and activated alumina. The term, particle-attaching material, is used because it is believed that an adsorption or an attraction between the relatively small particles actually occurs by reason of a charge on the particles or otherwise, although the invention is not to be limited by such theory. It should also be pointed out that for obtaining the most effective results, the particle-attaching material should be substantially the same size as the foreign particles.

The particle-attaching material or agent is introduced -into the pipe line or fluid conductor at various points along the length thereof such as indicated by the arrows at X in Figure 1 or at some point of the pipe line within a terminaloi station area. lThe particleattaching ma- The particle-attaching material then rthe pump 34 and a control valve 37 may also be proterial with the foreign particles attached thereto is reunits 15 (Figures 6 and 7) located at each of the terminals and stations just ahead of equipment to be protected such as the metering and delivery equipment to be protected usually found at pipe line terminals 14 or stations l2. The strainers l5 which are used may be of numerous types, but the one illustrated in Figures 6 and 7 is of the type disclosed in co-pending U. S. patent applications Serial Nos. 131,017 (filed December 3, 1949) now Patent 2,658,622 and 223,745 (tiled April 30, 1951) now Patent 2,670,658 and it will be described in detail hereinafter.

The preferred form of apparatus for injecting the filterv material or agent into the pipe line 10 is illustrated in Figure 2. The injector apparatus includes an inlet pipe 20 which is connected to the pipe line 10 for admitting all or a portion of the uid passing vthrough the pipe line 10 as well as the foreign particles such as corrosion products which may be present in the lluid. A control valve 2l is provided in the inlet line 20 for controlling the inlet of the iluid from the pipe line 10 to. the apparatus and for closing 0E such llow in the instances where the injection apparatus is not to be used. The fluid from thepipe line 10 flows through the inlet pipe 20 and is ultimately discharged into a mixing tank 23 through a pair of oppositely and tangentially disposed mixing inlet 'pipes 24 (Figure 5). The level of the lluid in the mixing tank 23 is controlled by a lioat 26 which is connected to a regulating valve 27 through suitable linkage 28. When the level of the fluid in the mixing tank 23 reaches a predetermined level, the oat 26 actuates the valve 27 to move same toward a closed position and further inlet of iluid from the pipe line 10 through the inlet pipe 20 is reduced gradually until the liquid level in the tank 23 begins to recede, at which time the valve 27 is gradually opened. Ordinarily, the float 26 will not be actuated to completely close the valve 27, but the lloat 26 and valve 27 serve as a safety device in rare instances to prevent overflow of lluid in the tank 23.

The particle-attaching material, is a powdered formy which is generally made up of granules of a size less than 40 microns, is initially placed in a hopper 30 from which the material is fed into the mixing tank 23 by a feeding device 31. The feeding device 31 may be any conven- 5 tional powder or granule feeding mechanism which is capable of continuously feeding desired quantities of powdered or granular material in accordance with predetermined settings of the device. The particle-attaching material is fed into the mixing chamber 23 simultaneously with the feeding of the petroleum liquid or other ud into vthe chamber 23 so that the filter material and the liquid are thoroughly mixed in the mixing chamber 23. The admixed particle-attaching material and the liquid in the mixing chamber 23 are carried through a return line or 5 pipe 33 by means of a suitable pump 34 to a return outlet o vided to stop or regulate return llow to the pipe line 10.

Thus, with the apparatus of Figure 2, it is possible to continuously inject particle-attaching material into the pipe line and to properly mix such material with the uid of the pipe line prior to its injection into the pipe line. In the usual case, it is desirable to vary the amount of the particle-attaching material which is injected into the pipe line 10 in accordance with the amount of foreign particles in the portion of the fluid being treated, and this can be accomplished by an electrical pickup indicator 40 of conventional construction which is capable of responding to the amount of foreign particles present in the fluid passing thereby. Electrical wires 41 from the pickup device 40 are in an electrical system with an electrical responding device 42 of known construction which is operated only when the amount of foreign particles in the fluid passing thereby changes; the operation of such device 42 causesa change in the rate of feed of the particlee forming material bythe feed device which corresponds with the change in the amount of foreign particles in the tluid, as will be explained.

In carrying out'the steps'of the method of this invention, the particle-forming material is injected into the pipe line l0'by the apparatus shown in Figure 2.

As stated above, although this invention is not limited to the removal of any particular foreign particles in a fluid, it is particularly suitable for the removal of iron and iron compounds, such asl the iron oxides, and/ or coloring matter in the form of particles, gel and the like, from petroleumuids. Iro'n oxides and iron compounds are particularly undesirable in pipe lines since they initiate corrosiontherein by attaching to the inside of a pipe and formng aA corrosion spot. The removal of the foreign particles,l such as the iron compounds or corrosion products, therefore serves the twofold purpose of cleaning the uid metered at or delivered from the terminals'or stations and. also removes materials which would initiate further and/or subsequent corrosion'or abrasion in the pipe line or'in the pipe line equipment.

vIt should also be pointed out that other treating materials, such as variousknown corrosion inhibitors, can

be injected withthe particle-attaching material into the of thev illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. The method of removing foreign particles including particles of a size less than 40 micron from petroleum liquid tlowing in a section of pipeline and from the interior of the pipeline itself without causing stoppage of vow or pressure drop which comprises the steps of, in-

jecting particulate particle-attaching material which has an attractiveness for the foreign particles in an amount .determined by the length of pipe and the concentration of foreign particles at the entrance to the section, and removing the pa/rticulate material with the collected foreign particles at the exit of the section.

2. The method as set forth in claim l, including the step of returning the cleaned liquid to the pipeline.

VReferences Cited in the file of this patent .UNITED STATES PATENTS Porter July 6, 1886 1,072,035 Richter Sept. 2, 1913 1,390,271 Booth Sept. 13, 1921 1,807,833 Eddy June 2, 1931 1,813,174 Lamb July 7, '1931 2,025,570 Clark Dec. 24, 1935 2,294,697 Seip Sept. 1, 1942 2,428,082 King et al Sept. 30, 1947 2,468,188 Frankenho Apr. 26, 1949 2,486,650 Hepp et al Nov. 1, 1949 FOREIGN PATENTS Great Britain Oct. .24, 1929 

1. THE METHOD OF REMOVING FOREIGN PARTICLES INCLUDING PARTICLES OF A SIZE LESS THAN 40 MICRON FROM PETROLEUM LIQUID FLOWING IN A SECTION OF PIPELINE AND FROM THE INTERIOR OF THE PIPELINE ITSELF WITHOUT CAUSING STOPPAGE OF FLOW OR PRESSURE DROP WHICH COMPRISES THE STEPS OF, INJECTING PARTICULATE PARTICLE-ATTACHING MATERIAL WHICH HAS AN ATTRACTIVENESS FOR THE FOREIGN PARTICLES IN AN AMOUNT DETERMINED BY THE LENGTH OF PIPE AND THE CONCENTRATION OF FOREIGN PARTICLES AT THE ENTRANCE TO THE SECTION, AND REMOVING THE PARTICULATE MATERIAL WITH THE COLLECTED FOREIGN PARTICLES AT THE EXIT OF THE SECTION. 